He told the UK Youth Parliament that exams were not getting easier and critics were sentimentalists harking back to a "mythical golden age".

Critics claim that the rising exam pass rates are evidence of "dumbing down".

But Mr Johnson told the meeting in Leicester that the nation should "take pride in these improvements".

He cited research showing that standards of grammar and punctuation had improved over the past decade.

'Harking back'

He has asked officials to create a national archive of exam papers so researchers can examine how the tests have changed and how they can improve in the future.

He said: "Despite the received wisdom of those that seek to detract from the achievements of our young people, research shows young people's performance is improving.

"Some people will always hark back to 'the good old days'.

"Sentimentality has its role in society, but I do not believe that role is to denigrate the hard work and efforts of the nation's children.

"Moreover, research shows that the so-called golden age is as mythical as Jason and the Argonauts.

"We are proud of what we have done to raise standards and will do more to make sure everyone is getting the best results they can.

"We want to know what we do well and where we need to raise our game."

Aptitude tests

Last year, the proportion of A*-C grades at GCSE rose by two percentage points to 61.2% - the largest such rise for 13 years.

At A-level only 3.8% of the 800,000 entries were failed, marking a 14.5% rise in the pass rate since 1995. Of these, 22.8% achieved an A grade - a 48% increase.

Many leading universities are setting their own aptitude tests, saying the A-level fails to discriminate between the brightest candidates because of the high numbers achieving the top grade.

Basic skills

Shadow secretary of state for education, David Willetts, responded: "Students are working hard and doing well. But ministers must not live in a fantasy world citing fantasy figures.

"Alan Johnson is relying on one report that only looked at a small part of the curriculum and specifically warns that trying 'to draw conclusions from this to overall GCSE standards is disputable'.

"In fact, Alan Johnson is trying to get away with a seriously misleading account of this report.

"Employers, universities and students themselves have warned that students are increasingly coming out of school without the basic skills or broad education they need to succeed in life. This does not mean our children are not working hard or meeting the exam requirements.

"But we do need to look at whether teaching to the test is now getting in the way of real education."